1. FIELD OF THE INVENTION
The present invention generally relates to a mortar mixer having a generally cylindrical, horizontally disposed, pivotally supported mixer drum constructed of plastic material and more specifically to improvements in the form of metal end plates attached to and rigidifying the plastic end walls of the generally cylindrical drum. The metal end plates are associated with the end walls of the plastic drum in a unique manner to reinforce and support the end walls of the plastic drum in order to provide adequate support for maintaining the shape and configuration of the generally cylindrical plastic drum during the entire procedure of placing materials to be mixed in the drum, mixing the materials and dumping the mixed materials from the drum.
2. Description Of The Prior Art
Mixers of the type utilizing a horizontally disposed mixing drum of generally cylindrical configuration which is pivotally supported from a mobile frame and which includes a power driven mixing blade assembly oriented within the drum in sealed relation thereto with the upper portion of the drum having an opening through which material may be placed in the drum and through which the mixed material may be discharged when the drum is tilted about a horizontal axis are well known and have been manufactured for use as mortar mixers, plaster mixers and fire proofing mixers and the like for a number of years. The following U.S. patents disclose various features of this type of mixer.
U.S. Pat. Nos. 3,761,058, 3,932,006, 3,905,519, 3,963,258, 3,931,748, 4,043,540, 4,180,281 PA1 U.S. Pat. Nos. 3,473,789, 4,521,116, 4,750,840, 4,761,076, 5,118,198, 4,877,327, 4,435,082, 4,491,415, 4,756,623, 4,569,648, 4,711,582
Recently, efforts have been made to construct the generally cylindrical mixer drum of plastic material such as high density cross linkable polyethylene or suitable equivalent plastic material rather than being constructed of relatively heavy steel which is subject to residual mortar sometimes being allowed to dry within the mixing drum which results in labor intensive removal procedures being required to break the mortar loose from the steel drum. The following U.S. patents relate to this field of endeavor.
As indicated by the above mentioned patents and as discussed in several of the patents, mixing drums constructed of polyethylene are not sufficiently strong to support materials above certain densities and volumes due to the lack of ridigity of the plastic material from which the drum is constructed. The above prior patents disclose attempted solutions to this problem by the introductions of cradles or reinforcing frame members associated with the generally cylindrical polyethylene drums. However, the above prior patents do not disclose the concept of the cylindrical drum being constructed of polyethylene combined with rigid metal end plates connected with the end walls of the polyethylene drum with the metal end plates being associated with the end walls of the drum in a unique manner to rigidify the end walls and cylindrical drum in order that it can be used effectively with heavier or more dense materials and larger total weight of materials being mixed.